Hydraulic power units are used to convert and transmit power between devices and many types of equipment. A hydraulic pump can convert the power of an electric motor into a flow of high pressure hydraulic fluid that can be used for performing a useful function in a machine. Hydraulic power units are typically used in aircraft to control air foils, valves and actuators. Shaft rotation speed and shaft torque are typically measured to determine performance of the hydraulic power units and to insure that new hydraulic power units meet design and manufacturing specifications. One common technology available for measuring the torque experienced by a rotating shaft includes a series of strain gauges bonded in strategic locations to the shaft. The electrical signals that are produced by the strain gauges are often transferred from the rotating shaft to the fixed portion of a machine through a series of slip rings or inductive coils.